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Abstract

Health Issue

Smoking among Canadian women is a serious public health issue. Using the 1998–99 National
Population Health Survey, this study examined underlying factors contributing to differences
in prevalence of smoking among subgroups of women and men, and its effects on self-reported
indicators of health.

Key Findings

In Canada, 26.4% of women and 29.2% of men were classified as current smokers. Higher
levels of education and income were associated with decreased odds of current smoking.
Adjusting for all other factors, being an ethnic minority decreased the odds of current
smoking for both men and women (OR:0.35, 99%CI:0.23–0.54; OR:0.13, 99%CI: 0.09–0.20
respectively). Single mothers had the highest odds of smoking (OR: 2.12, 99%CI: 1.28–3.51)
when compared to married mothers with children under 25 years of age. Current women
smokers and current and former men smokers were less likely to report very good or
excellent health compared with never smokers (OR: 0.83, 99%CI: 0.70–0.98; OR: 0.49,
99%CI: 0.41–0.60; OR: 0.75, 99%CI: 0.63–0.90 respectively). Women who were current
smokers had increased odds of needing health care and not receiving it (OR: 1.50,
99%CI: 1.10–2.05).

Data Gaps and Recommendations

Key issues for Canadian women include an increased prevalence of smoking among young
girls and the strong association between smoking and social and economic disadvantage.
Tobacco control policies and programs must target high-risk groups more effectively.
Of particular importance is the development of programs and policies that do not serve
to reinforce existing inequities, but rather, contribute to their amelioration.

Background

Smoking among Canadian women is a serious public health issue. Although historically
men have smoked more than women, the decline in smoking prevalence among men has been
much more pronounced over the last few decades: down from 61% to 25% among men from
1965 to 2001, as compared with a reduction in prevalence from 38% to 21% over this
period among women. [1] The secular pattern of smoking places Canada in the fourth stage of the tobacco epidemic,
along with other countries of the developed world such as the United States, the United
Kingdom, Western Europe and Australia. [2] This stage is characterized by a decline in smoking prevalence among both men and
women, accompanied by a peak and subsequent decline in deaths attributable to smoking
among men. For women, however, the peak and subsequent decline in smoking-related
deaths lags behind men by approximately 20 years. To date, there is no evidence to
substantiate that this peak has been achieved among Canadian women.

Ongoing surveillance of smoking prevalence has been conducted in numerous Canadian
national and provincial cross-sectional surveys. [3-7] Smoking prevalence is typically presented in sex-disaggregated, and to a lesser extent,
sex- and age-disaggregated format. Similarly, smoking-related mortality outcomes and
some morbidity outcomes, such as cancers, have been adequately captured by age and
sex. However, we have only recently begun to acknowledge and understand smoking and
its health effects from a gendered perspective. Whereas sex is biologically determined,
gender is socially constructed and influences our roles in society, our formation
of identity and the way in which others respond to us. [8,9] An analysis of smoking that incorporates social, cultural and economic factors can
illuminate its differential impact on the lives of subgroups of women and men. In
addition, there are many health consequences attributed to smoking, yet only the long-term
consequences, such as lung cancer, heart disease and respiratory problems, are typically
considered. These outcomes occur in older age groups and hold little relevance outside
these age groups. More subtle health effects due to smoking may be particularly important
to consider for young and middle-aged adult smokers because they are meaningful in
the context of their daily lives. Health indicators that reflect intermediate health
outcomes due to smoking, such as restriction of activities or use of health services,
have rarely been emphasized.

The purpose of this paper, therefore, was to examine smoking prevalence and selected
smoking-related health indicators for specific subgroups of women and men, incorporating
socio-economic determinants of health to consider more fully the impact of gender.
Based on identified gaps in the literature, the following research questions were
posed: (1) What are the differences in prevalence of smoking among subgroups of women
and men, based on determinants of health such as geographic location, age, income,
education and ethnicity? (2) Are there differential effects of smoking on selected
self-reported indicators of health for women and men? A summary of the literature
is followed by an analysis of data from the NPHS.

Smoking Demographics and Trends

Dramatic variations in rates and trends of smoking are evident for specific subpopulations
of women in Canada. There has recently been a disturbing trend whereby smoking rates
among teenaged girls exceeded smoking rates among teenaged boys for the first time.
[10] Among girls aged 15 to 19, 25.1% reported being daily smokers in 1998–1999 and 26%
in 2001, as compared with 18.5% and 20% respectively for boys in this age group. [5,6] Girls also started smoking at a younger age, 41% of girls aged 15 to 17 reporting
having smoked their first cigarette before age 13 as compared with 29% of boys. [10] In the last decade, daily consumption increased for girls aged 15 to 19 from 11.5
cigarettes per day in 1990 to 12.7 cigarettes per day in 1999; this has decreased
to 10.8 in 2001. [6,10]

The association found between smoking and social and economic disadvantage is in accordance
with the tobacco epidemic model. There is a clear socio-economic gradient with cigarette
smoking: higher prevalence among women who live in low-income households, have low-status
jobs or are unemployed, are lone parents or divorced, and have low levels of education.
[11,12] High prevalence rates of smoking among pregnant women are of particular concern.
Pregnant smokers tend to be younger, have low levels of education, reside in poorer
neighbourhoods, and are more likely to be single compared with their non-smoker counterparts.
[13-20]

Aboriginal peoples have the highest rates of smoking in Canada. In 1997, 62% of First
Nations people and 72% of Inuit were smokers compared with 29% of the general Canadian
population. [21] The 1996 NWT Alcohol and Drug Survey showed that within the Northwest Territories,
smoking prevalence was 44.2% and rates were similar among men and women, at 52.0%
and 49.7% respectively. For those aged 15 to 24, the prevalence of smoking was 64.3%
compared with 32.4% for this age group nationally. In Nunavut, overall smoking prevalence
was 63.9%, with a prevalence of 77.9% for those aged 15 to 24; gender-specific rates
for age groups were not reported. Equally alarming is that smoking rates among First
Nations and Inuit are not decreasing: the prevalence of 62% reported from the First
Nations and Inuit Regional Health Survey in 1997 was unchanged from the Statistics
Canada estimate of 62% reported from the Aboriginal People's Survey carried out in
1991. [7]

Higher rates of smoking have also been observed in Francophone populations compared
with Anglophone women. The most recent information available for the Canadian Francophone
population comes from a report on the smoking behaviours of Canadians based on the
1996–1997 NPHS. [22] The prevalence of smoking was 35% among Francophones aged 15 and up, markedly higher
than the Canadian average of 26%. Among Francophone women, the prevalence rate was
35% as compared with 36% among Francophone men and 24% among Anglophone women. Of
all Francophone women in Canada, Quebec women had the highest smoking prevalence (38%).
Between 1985 and 1995, smoking prevalence had dropped among Francophone women by 3%,
as compared with a drop of 7% among men.

The Health Effects of Smoking

The number of deaths due to smoking-related illnesses has increased in Canada over
the last decade, with a much steeper increase seen in women than men. [23] This paradox, of increasing smoking-related morbidity and mortality in the face of
declining prevalence, is a consequence of the steady increase in smoking prevalence
among women in earlier decades. The impact on health is now evident in the rising
incidence of cancers, heart disease and respiratory diseases among women. The number
of deaths attributable to smoking has increased by 77% for women, from 9,009 in 1985
to 15,986 in 1996, whereas the number among men increased only slightly over a similar
time period. [10] In 1996, the three leading causes of death in both men and women were cancer, heart
disease and cerebrovascular disease, of which 21% was attributable to smoking. [23] Smoking is also known to increase the risk of lung cancer, which overtook breast
cancer as the leading cause of cancer mortality among Canadian women in 1993. [10]

Adverse effects of smoking have been documented for the female reproductive system
and health states unique to women such as pregnancy, breast-feeding and fetal health.
Smoking during pregnancy has been found to decrease placental blood flow and has been
associated with intrauterine growth retardation, increased rates of perinatal death,
complications of pregnancy, and fetal anomalies such as cleft lip and palate. [24,25] On average, the infants of women who smoke have a lower birth weight, reduced length,
smaller head circumference and reduced gestational age than the infants of non-smoking
women. [15,18] A significant negative correlation between the number of cigarettes smoked and birth
weight has been demonstrated. [15]

Smoking has also been implicated in the etiology of diseases unique to women, such
as cervical and breast cancer, [26,27] and diseases of higher prevalence among women, such as osteoporosis. [28] Respiratory conditions such as asthma, bronchitis and emphysema are known to be adversely
associated with smoking and are more prevalent among female than male smokers. [12,29] From 1979 to 1994 in the United States, age-adjusted mortality from chronic obstructive
pulmonary disease (COPD) decreased by 17.1% among men but increased by 126.1% among
women. Women also had a significantly higher hospitalization rate for COPD than men
when amount of smoking was taken into consideration.

Methods

Various surveys are available in Canada that examine smoking and tobacco use, such
as CTUMS (Canadian Tobacco Use Monitoring Survey) and the General Health Survey. For
the purposes of this chapter, NPHS data were used because more comprehensive information
on social determinants of health were required for a gender analysis. A secondary
analysis of existing cross-sectional data from the NPHS 1998–1999 was undertaken.
[5] The methods of data collection for the NPHS have been reported in detail elsewhere
[30] and are described in Appendix A. The third wave, completed in 1998–1999, was conducted
by telephone.

Statistical Analysis

For this report, analyses were limited to respondents aged 15 and over from the health
component of the survey, weighted to represent approximately 24 million Canadians.
For all analyses conducted, probability weights provided in the NPHS microdata files
documentation were used to account for the sample design. For all reported proportions,
the approximate coefficients of variation provided by NPHS were checked and found
to be within the acceptable range (CV 0%-16.5%). Confidence intervals were calculated
using the approximate CVs. For regression analyses, the probability weights were rescaled
to an average value of one in order to improve the variance calculation. While this
procedure does not take into account stratification or clustering of the sample design,
it does take into account unequal probabilities of selection. [30] In addition, rather than using 95% confidence intervals, the more stringent 99% confidence
intervals were reported. Maximum-likelihood multinomial polytomous regression and
logistic regression were used for multivariate analysis with non-smokers as the referent
group.

Measures

All variables were based on pre-defined categories used in the NPHS. Additional detail
regarding these variables is available in the NPHS documentation. [30]

Smoking status was characterized as never, current or former on the basis of questions
about whether individuals smoked cigarettes daily, occasionally or not at all, at
present or ever. Income adequacy is a measure incorporating total household income
and the number of people within the household. This variable was collapsed from five
categories to three categories for multivariate analysis: "low" and "low middle" categories
were combined into "low," and "middle" and "upper middle" categories were grouped
into "middle." Marital status was grouped into three categories based on the presence
of a partner. Education was regrouped for multivariate analysis into three categories
by combining secondary and some post-secondary education categories in the original
variable.

Household type groupings reflect a relationship matrix derived in the NPHS. [30] For the multivariate analysis, six categories from the original NPHS variable were
combined to form four categories: "couple with children < 25" included "couple with
children < 25" and "couple with children < 25 plus others"; "couple with children
> 25" included "couple with or without children > 25" and "couple alone"; the remaining
two categories did not change. An overall functional social support scale, constructed
for the Medical Outcomes Study (MOS), was used for the present analysis. It incorporated
four subscales measuring tangible social support (range 0–16), affection (0–12), positive
social interaction (0–16) and emotional/informational support (0–32).

Geographic location reflected the urban classification used in the NPHS, in which
rural was defined by Enumeration Area classifications, and Census Metropolitan Area
(CMA) designation was used to identify residents in Montreal, Toronto and Vancouver.
Visible ethnic minority status was determined according to whether individuals identified
themselves as "White" or "Other."

The outcomes considered were primarily health indicators reflecting the intermediate
consequences of smoking rather than disease states. These outcomes were restriction
of activities, self-rated health, sense of coherence (a self-rated measure of mental
health), consultation with health professionals, and health care needed but not received.
Number of chronic conditions was also considered. Restriction of activity was based
on the question "Because of a long term physical or mental condition or a health problem,
are you limited in the kind or amount of activity you do?" Self-rated health status
was measured using the Health Description Index, in which respondents report their
health as being poor, fair, good, very good or excellent. This measure was collapsed
for the multivariate analysis into two categories "poor/fair/good" and "very good/excellent."
The Sense of Coherence (SOC) scale was used in the NPHS as an indicator of mental
well-being, incorporating aspects of comprehensibility, manageability and meaningfulness.
Stephens et al. defined scores equal to and above the 75th percentile as indicating
high SOC. [31] Following this method, a score of 70 in the NPHS 1998–1999 data indicated the 75th
percentile, and a dichotomized variable was constructed for the multivariate analysis
to reflect this (scores of 70 and above indicate high SOC; scores below 70 indicate
low SOC).

Results

Socio-demographic Characteristics

The socio-demographic characteristics of never smokers, former smokers and current
smokers are presented for women and men in Figures 1 and 2 respectively. Overall, 26.4% of Canadian women and 29.2% of Canadian men were classified
as being current smokers. Among women, the highest proportion of current smokers (34.0%)
was in the 15 to 24 age group, whereas for men the highest proportion (34.4%) was
in the 25 to 44 age group. While the difference in proportions of current smokers
differed only slightly for women and men aged 65 and older (11.9%: 95% confidence
interval [CI] 9.7, 14.1, and 14.8%: 95% CI 12.0, 17.6 respectively), very different
patterns of lifetime smoking history were noted: the majority of women of this age
group had never smoked (53.7%: 95% CI 50.3, 57.1), whereas a much smaller proportion
of men had never smoked (21%: 95% CI 17.8, 24.2). This is a function of historical
gender differences in smoking uptake and cessation, as well as survival.

Figure 1. Socio-demographic Characteristics of Never Smokers, Former Smokers and Current Smokers:
Women (NPHS 1998–1999)

Figure 2. Socio-demographic Characteristics of Never Smokers, Former Smokers and Current Smokers:
Men (NPHS 1998–1999)

The prevalence of smoking among women and men of visible ethnic minorities was lower
than among non-minority women and men; this difference was most pronounced among women
(28.8%: 95% CI 27.4, 30.2 versus 9.5%: 95% CI 8.7, 10.3 for non-minority and minority
women respectively). The prevalence of smoking according to level of education was
similar among women and men, in that there were considerably lower rates of current
smoking among those with the highest level of education (20.9%: 95% CI 19.0, 22.8,
and 24.0%: 95% CI 21.9, 26.1, among women and men with post-secondary education respectively).
A gradient was also noted for income adequacy, whereby smoking prevalence was lower
for each increasing level of income adequacy. Interestingly, although the prevalence
of smoking among women and men was similar in the high income adequacy category, the
difference between women and men was more marked in the lowest income adequacy category,
in which men were shown to have a higher prevalence of current smoking (44.5: 95%
CI 37.3, 51.7 versus 33.7%: 95% CI 27.6, 40.0 among men and women respectively).

The prevalence of smoking varied by marital status and was lowest among those who
were married (22.1%: 95% CI 20.5, 23.7 among women and 26.5%: 95% CI 24.9, 28.1 among
men). When smoking was examined by household type, the highest prevalence of current
smoking was seen among women and men heading lone-parent families (40.5%: 95% CI 36.8,
44.2 and 39.5%: 95% CI 33.8, 45.2, among women and men respectively).

Figure 3 presents the results of multivariate analyses using polytomous regression to examine
the association between socio-demographic factors and smoking status for women and
men, adjusted for all other variables in the model. The modelling was done separately
for women and men to determine the most parsimonious sex-specific models. The final
model for women included two variables, household type and functional social support,
that did not significantly contribute to the association for men. For the purposes
of comparison, the same model was presented for both men and women. Associations for
former smokers and current smokers compared with never smokers are presented for completeness,
but the discussion addresses differences between current smokers and never smokers
only.

Figure 3.Multivariate Association Between Socio-demographic Factors and Smoking Status (Former
and Current Smoking Compared with Never Smoking), by Sex (NPHS 1998–1999).

*OR = odds ratio;

**Married/common law/partner

†Widowed/separated/divorced

Older age was associated with a decreased odds of current smoking for both men and
women, with women aged 45 and up and men aged 65 and up less likely to be current
smokers compared with those aged 24 to 44. Being of an ethnic minority also decreased
the odds of current smoking for both men and women (odds ratio [OR]: 0.35, 99% CI
0.23, 0.54; OR: 0.13, 99% CI 0.09, 0.20 respectively). Women and men who had completed
post-secondary education had a decreased odds of current smoking compared with those
who had less than a secondary school education (OR: 0.50, 99% CI 0.37, 0.67; OR: 0.39,
99% CI 0.28, 0.55 respectively). Individuals in higher income adequacy categories
were less likely to be current smokers, although for women this association achieved
borderline statistical significance (women: OR: 0.68, 99% CI 0.45, 1.02; men: OR:
0.48, 99% CI 0.31, 0.76). Women in all household types other than those consisting
of couples with children under 25 had increased odds of being current smokers, and
single mothers had the highest odds (OR: 2.12, 99% CI 1.28, 3.51). For men, only single
status increased the odds of being a current smoker (OR: 1.75, 99% CI 1.07, 2.84).

Health Indicators

We then examined the proportions of never smokers, former smokers and current smokers
who reported a variety of health indicators (Figure 4). Men who were current smokers, men who were former smokers and women who were current
smokers were less likely to report very good or excellent health than never smokers,
and less likely to obtain a high score on the SOC index than never smokers. Greater
proportions of current and former smokers than never smokers indicated that a long-term
limitation restricted their activities. The majority of individuals had consulted
with a health care professional in the previous year, but men who were current smokers
and those who were never smokers had done so the least (86.6%: 95% CI 87.7, 90.5 and
89.1%: 95% CI 85.0, 88.2 respectively). Almost double the proportion of women current
smokers reported needing health care but not receiving it (11.1%: 95% CI 9.3, 12.9
and 6.9%: 95% CI 5.5, 8.3 among women and men respectively). Women who were current
smokers and those who were former smokers reported the highest proportions of two
or more chronic conditions (40.5% and 43.9% respectively, compared with 24.3% and
34.1% of men).

Figure 4. Current Health Indicators for Never Smokers, Former Smokers and Current Smokers, by
sex (NPHS 1998–1999)

Lastly, we examined the association between smoking status and each health indicator
separately for men and women, adjusting for the previously considered socio-economic
factors by means of logistic regression (Figure 5). Current women smokers and both current and former men smokers were less likely
to report very good or excellent health compared with never smokers (OR: 0.83, 99%
CI 0.70, 0.98; OR: 0.49, 99% CI 0.41, 0.60; OR: 0.75, 99% CI 0.63, 0.90, respectively).
Likewise, women and men who were current smokers were less likely than their non-smoking
counterparts to report high sense of coherence (OR: 0.74, 99% CI 0.61, 0.90; OR: 0.72,
99% CI 0.59, 0.89 respectively). Women who were current and those who were former
smokers had similar odds of borderline statistical significance of having one or more
chronic conditions (OR: 1.14, 99% CI 0.95, 1.36; OR: 1.17, 99% CI0.99, 1.39 respectively);
only male former smokers had increased odds (OR: 1.33, 99% CI 1.12, 1.58). Former
male smokers had increased odds of medical consultations (OR: 1.60, 99% CI 1.18, 2.17)
compared with never smokers. Female current smokers had high odds of needing health
care and not having received it (OR: 1.50, 99% CI 1.10, 2.05). Current smokers and
former smokers had increased odds of restriction of activities compared with never
smokers.

Discussion

In this study, which used data from a population-based, national survey conducted
in 1998–1999, we found smoking prevalence to be high for particular subgroups of both
women and men that have previously been identified in the literature: younger age
groups, lower income adequacy groups and lone-parent households. Despite the overall
lower prevalence of smoking among women than men, the proportion of young women smokers
exceeded that of men.

Age, marital status, ethnicity, education and income adequacy independently contributed
to an association with current smoking for women and men. Age, ethnicity and marital
status had strong associations for women, whereas education and income adequacy were
strong factors for men. Interestingly, household type and functional social support
contributed to the association with current smoking for women but not for men. The
differences in these factors between women and men may reflect differences in life
experiences in terms of social and family roles, work and care-giving. However, the
fact that independent associations between socio-economic factors and smoking were
seen for both women and men attests to their universal impact and may help to explain
the high rates of smoking seen among subgroups that are disadvantaged in multiple
aspects, such as Aboriginal populations.

In addition to considering the prevalence of smoking and the associated odds within
subgroups of women and men, it is also important from a public health perspective
to consider the population estimates within those subgroups. When the population estimates
of lone parents are considered, there are many more women who are lone parents than
men. This higher prevalence, combined with a strong magnitude of association between
lone-parent status and smoking for women, implies that this group is at particularly
high risk of smoking-related health problems.

In this study, associations between smoking and self-reported indicators of health
were examined. Whereas the long-term effects of smoking on outcomes such as heart
disease, cancer and respiratory conditions are well established, there are many more
proximate effects of smoking that go unrecognized and that may differentially affect
women and men. This study investigated six of these measures in order to explore these
secondary, but important, differences. Women smokers reported greater restriction
of activities, poorer mental health and more chronic health conditions than men who
smoked. Although a greater proportion of women than men had consulted with a health
professional in the previous year, twice as many women as men felt that they had health
care needs that were not met. As compared with never smokers, independent associations
were seen between current smoking and lower self-rated health, poorer mental health
and greater restriction of activities for both women and men. Despite the higher prevalence
of adverse health conditions noted among women as compared with men smokers, the higher
background rates of health conditions among women often resulted in weak associations.
This may reflect underlying gender differences in health; for example, women's perceptions
of illness. However, it may also be the result of different patterns of smoking among
men and women in terms of amount smoked and duration of use, which we were unable
to account for.

It is relatively easy to compile information based on age and sex but more difficult
to capture data from the complex range of factors that contribute to the impact that
gender has on smoking and its health effects. While the present study made an attempt
to capture some of these underlying factors, the difficulty of adequately measuring
them remains. Examples of this include gender issues surrounding self-reported health,
perceptions of the adequacy of access to health care and the gender-related nature
of utilization of the health care system. Another issue is our lack of data, gender-related
or otherwise, regarding ethno-cultural groups. We know from previous work among ethnic
subpopulations in Canada and elsewhere that there are very different rates of smoking
according to ethnic background and race, yet we have been unable to adequately document
these aspects in population surveys in Canada. As a result, we are unable to provide
sex- and gender-differentiated statistics to various minority groups that desperately
seek information on their health status.

It is important to recognize that we used data from the 1998–1999 NPHS, a cross-sectional
survey. This precluded us from assessing the long-term health sequelae of smoking,
and it also meant that the associations documented cannot be interpreted as causal,
since the appropriate temporal relation between smoking status and health indicators
cannot be firmly established. Indeed, the associations observed may be due to self-selection
effects rather than the effects of smoking per se. For example, it is possible that
poor mental health in smokers may be the result of people with recurrent depression
using smoking to achieve the stimulant effects of nicotine. Similarly, SOC may be
a predictor rather than an outcome of smoking. It is also difficult to interpret the
results for former smokers, as it is reasonable to expect that former smokers reflect
two very different types: those who quit prior to a change in health status, and those
who quit as a consequence of an adverse health outcome. Finally, by choosing to use
the more stringent 99% confidence limits we may have missed some true associations.

In summary, smoking is one of the strongest modifiable risk factors for a host of
health outcomes that contribute to female morbidity and mortality in Canada and worldwide.
The contribution to the literature that this study provides is the control of potential,
confounding socio-economic characteristics in a multivariable analysis examining smoking
and smoking-related health outcomes for both women and men. Key issues for Canadian
women include an increased prevalence of smoking among young girls and the strong
association between smoking and social and economic disadvantage.

Recommendations

The high prevalence of adverse intermediate health outcomes noted for women smokers
is worthy of further investigation. Examining and acknowledging the importance of
studying smoking and its health sequelae in a sex- and gender-differentiated manner
is a valid starting point, but is clearly not enough. Further work remains to be done
on the development of well-constructed socio-demographic and socio-economic health
indicators that can be routinely collected and analyzed in population-based surveys
to elucidate the impact of sex and gender on women's health in relation to smoking.
For example, data that adequately capture the complexity of issues that women face
in terms of occupation and employment status – balancing paid and unpaid work and
caregiving roles – are likely to contribute to an understanding of smoking and smoking-associated
health outcomes. The knowledge gained can then be used to inform the development of
tobacco control policies and programs that may target high-risk groups more adequately
and effectively. Of particular importance is the development of programs and policies
that do not serve to reinforce existing inequities but, rather, contribute to their
amelioration.

Note

The views expressed in this report do not necessarily represent the views of the Canadian
Population Health Initiative, the Canadian Institute for Health Information or Health
Canada